Thermostat.



No. 794.497. PATENTED JULY 11, 1905. J. D. GOULD.

THERMOSTAT.

APPLICATION FILED 0012s, 1904.

Wl-INEEEEE. ipk/ENTE@ cg fig/J, 6%@ W Patented July 11, 1905.

PATENT OFFICE.

JOHN GOULD, OF NEW YORK, N. Y.

THERMOSTAT.

SPECIFICATION forming part of Letters Patent No. 794,497, dated July 11,1905.

Application iled October 8, 1904-.. Serial No. 227,748.

To aZZ whom, it may concern,.-

Beit known that I, Jol-1N D. GoULD, a citizen of the United States ofAmerica, and a resident of the city of New York, borough of l Brooklyn,in the county of Kings'and State of New York, have invented a new andImproved Thermostat, of which the following is a speciiication.

The invention relates to thermostats for use in fire-detecting circuits;and it consists of a small plate of metal of relatively low fusingpointarranged between two pieces or plates of metal of relatively highfusing-point and with a sheet of porous insulating material interposedbetween the low-fusing plate and one or both of the high-fusing plates,an insulating envelop around the periphery of the lowfusing metal plateto prevent lateral ow of such metal when fused under the iniiuence ofheat and to cause it to How through the interstices of the porous sheet,by which electrical connection will be made between the two plates ofhigh-fusing metal and thereby close the alarm-circuit through metallicterminals with which the high-fusing metal plates are connected. Alsofor the purpose of obviating an accidental failure of the low-fusingmetal when melted to make the electrical connection between the twoplates of high-fusing metal a spring may be employed to press one of thelatter plates constantly toward the plate of low-fusing metal and bythat means cause the high-fusing plate to occupy the space which mayhave been left by the flowing away of the fused metal and at the sametime assist in forcing suchfused metal through the porous sheet.

In the drawings which form a part of this specification, Figure 1 is acentral sectional elevation of a convenient embodiment of this inventionin which a spring is provided to insure continual contact between theplates of high-fusing and low-fusing metal. Fig. 2 is a plan of the baseof the thermostat shown in Fig. l removed from the cap and viewed fromabove. Fig. 3 is a sectional elevation of my improved thermostat Withoutthe use of a spring to act upon the metal plates. Fig. 4 is a plan ofthe metal portions of the thermostat shown in Fig. 3 looking downwardthereon, the outer broken-line circleindicating the outline of the baseof insulating mavplates L Z, as also the metal stem 7b3, which in thisconstruction I find convenient to use for the bearing of the spring s,which is connected with the stem 71,3 by means of a nut n, secured upona screw on the upper end of the stem lia. The spring s is electricallyconnected with a terminal t by a screw s, which passes through the baseB and engages the metal terminal t. rIhe metal chamber O is connectedwith another terminal Z by means of a metal strip m and another screw s,which passes through the base B.

c c' are the circuit-wires.

In Fig. 3 the metal strip s2 has not the spring action of the part s inFig. l, but at the same time serves as an electrical connection betweenthe metal plate it and the terminal Z and has a bearing upon the plateZ1. at d. Under usual conditions when the thermostat shown in Fig. 3 issubjected to heat sufhcient to fuse the metal plate Z that metal byreason of its eX- pansion will be forced through the interstices orpores of the sheet p and make electrical connection between the plateand the cap ZL', thereby completing the circuit through the terminal t,metal strip s2, plates Z, Z, and ZL', and thence to the terminal Z,which in this instance is upon the flange of the metal chamber O, and,as illustrated in Fig. l, when the plate of fusible metal Z is meltedthe action of the spring s upon the plate ZL, through the stem h3, willtend to force the fused metal Z through the interstices of the sheet p,so as to make electrical connection between the plate ZZ and the cap t,the surrounding en- A velopz' preventing the iiow of the metal Zlaterally, the same in the construction shown in Fig. l as that shown inFig. 3.

The principle of operation of this thermostat is the same as thatembodied in the thermostats shown in my Patent No. 771,144 of September27, 1904, and other patents granted to me in respect to theemploymentotl the flow of the fusible metal when melted through anintervening insulating porous sheet or envelop; but the construction andarrangement or' the parts is different, and the plate ot' metal of lowfusing-point can be m'ore readily and conveniently renewed whenever ithas been melted, distorted, or disarranged by the influence of heat. Itwill be observed that this may be done by simply unscrewing the metalcap It and inserting a new plate and insulatingsheetp in their properplace within the insulating-envelop z' and screwing the cap L back inplace.

I claim- 1. 1n an electrical thermostat, a metal plate of relatively lowfusing-point and a relatively porous insulating-sheet upon one sidethereof, the two located between two metal plates of relatively highfusing-point in close contact therewith, an insulating-chamber whichperipherally incloses the plate ot' low-fusing metal, and a terminal fora circuit-conductor electrically connected with each high-fusing plate,'for the purpose described.

2. In an electrical thermostat, a metal plate of relatively lowfusingpoint, located between a metal plate ot' relatively highfusingpoint, and a sheet of porous insulating material, the wholecontained within a chamber ot' metal of relatively high fusing -point,but electrically insulated therefrom, and metallic terminalsrespectively electrically connected with the high-fusing plate and theinclosing metallic chamber.

3. In an electrical thermostat, a metal plate of relatively lowfusing-point, located between a metal plate of relatively highfusingpoint, and a sheet of relatively porous insulating material, thewhole within a chamber of metal of relatively high fusing-point, butelectrically insulated therefrom, a spring which tends to press theplates of high and low fusing metals together and terminals electricallyconnected respectively with the plate ot' high-'fusing metal and themetal chamber.

JOHN l). (irOULI). `W itnesses:

HENRY L. VASHBURN, HERBERT D. MONTGOMERY.

